One of the reasons why Naruto such a great manga.
Naruto is famous for its large gallery of villains. such as Kurama or Orochimaru, are later redeemed, and even those who don't find salvation in life, such as Itachi or Pain, still have a redeeming moment in which their motivations are made clear. The one exception is, perhaps, the very last villain, Kaguya Otsutsuki, who was not really well fleshed out due to appearing towards the end of the manga.
One of Boruto's most questionable decisions, in fact, was that it did not endeavor to create new villains, but it just recycled Naruto's last one. Even if it is not actually Kaguya but other of the of Kara, but until now they are just empty villains whose sole purpose is to fight against the heroes. Readers still know nothing about Boro and Delta, for example, while the true motivations behind Amado's actions still have to be revealed (and he is no longer a villain, but an ally).
Even Code, who is the current main antagonist in the manga, has the only desire to carry on Isshiki's will and get revenge on those who killed him. His backstory hasn't been revealed, besides the fact that he was one of the candidates for becoming Isshiki's vessels. He is essentially just a continuation of the previous villain, Isshiki, in a new body. This is clearly very different from Naruto's Pain's heartbreaking flashback, or Itachi's complex and dramatic background. One of Naruto's most criticized decisions, in fact, was to introduce a new ultimate villain (Kaguya) at the very last moment, taking the spotlight away from who was supposed to be the actual final villain, Madara Uchiha.
Boruto's decision to use the Otsutsuki as the main villains is one of the biggest flaws of the manga. Not only Boruto recycled Naruto's worst villain, but in doing so it failed to build on its predecessor's greatest strength, the capacity to develop believable, well-rounded antagonists, whose motivations and backstories made them always stand out.
